By Michael Smith, Contributing Author
When should we start thinking about winter maintenance for gravel roads? The real question should be: Do we ever stop?
Winter Maintenance should be thought of with every aspect of gravel road maintenance. Mowing back vegetation in the summer months will provide more sunlight for the colder moths and help promote melting. Installing culverts, drop inlets and other drainage will also be of benefit come winter.
However, the three most important maintenance techniques on gravel roads are drainage, drainage and drainage.
Drainage should start at the center of the road with the crown. Some agencies I have spoken with remove or lower the crown for the winter months.
The thought process behind this is that with less crown there is less tendency to slide off the road. If vehicles are sliding off the road, it is usually because the road has ice on it.
Unless there is a current freezing rain event, ice comes from standing water. Standing water comes from a lack of crown. Paved roads keep their crown in the winter and so should gravel.
If the temperature allows for any melting, gravel roads should have sufficient crown to move that water towards the ditch.
How much is enough? The South Dakota manual on gravel road maintenance, as well as Matt Ulberg, director of Montana’s Local Technical Assistance Program (LTAP), state that it’s a half-inch per foot.
I concur. Less than a half-inch per foot leads to water staying on the roadway and creating hazardous conditions for winter driving.
When gravel roads freeze, there are a few different things to consider. Melting agents or chlorides might be the most important item. Any type of melting agent used on a gravel road will have little time to dilute before entering the environment.
All melting agents should be limited in their use on gravel roads. They can also cause an otherwise frozen gravel road to begin thawing. This makes plowing difficult, and it damages the road and plow equipment.
Abrasives or sand can be used as a traction agent. The type of sand that is applied should be chosen with year-round maintenance in mind. I recommend a minimum of a half-inch minus crushed sand for winter gravel roads. This adds a more robust traction agent.
Any material that is pushed or plowed to the shoulder can be brought back onto the road in the spring with the use of a grader. When creating a sand specification, keep the passing at the 200 sieve low — 4% or less for a higher quality, course winter sand.
Plowing gravel roads in the late fall and early spring can be challenging if the roads are not frozen.
Plowing muddy gravel roads is like trying to shave a wet sponge. The use of better plow blades for gravel roads is something I implemented when I was a department of public works director. We called them mud plows.
In simple terms, it is a standard plow with a plow blade or “cutting edge” that is folded back. This allows the plow to float along the top of the road without gouging or biting in.
One way to accomplish this is to build them. Start by removing the existing plow blade. Have a piece of angle iron stamped out to match the hole spacing of your plow and blade. Have both angles stamped out. Bolt the angle iron to the plow and the plow blade to the other edge of the angle iron.
Another option is to purchase a bolt on blade made for sensitive pavements.
Winter maintenance on gravel roads has its own complexities and requires different techniques than paved roads.
It is important to devote the needed time to plan and implement a winter maintenance program for gravel roads. This decreases the environmental and economic impacts and allows for a higher level of service.
A gravel road may not seem like a high priority road to some, but to those who live on one it sure is. RB
Michael Smith is the technical training specialist at the University of Massachusetts Transportation Center.
